Proper Draining of Raised Planting Beds

Raised planting beds are often used by gardeners with limited mobility or with knee and joint pain. The position of the beds does not require a gardener to spend time on their hands and knees. Plants also benefit from raised planting beds. Many plants which cannot thrive in compacted, heavy soils do well in raised beds. Gardeners are able to manipulate soil conditions by adding necessary soil amendments which promote free root development and healthy plant growth.

Choose the site of your raised bed with drainage in mind. Placing the raised bed in a marshy area or in a depression increases the risk of drainage problems. These problems are often hidden as water slowly collects in the bed creating less than optimal growing conditions. Plants will exhibit symptoms of root rot such as limp, discolored leaves. Insect, fungal and bacterial infestations will develop. Even if the bed is not situated in a depression or marshy area irrigation water from sprinkler heads and hoses can cause similar problems.

Gardeners solve the problem of waterlogged planting beds by incorporating drainage within the design of the structure. Gardeners can drill holes into the bed's frame. Do this prior to filling the bed with soil. Drill ? inch holes every two feet along the base of the structure. Line the interior of the bed with landscape fabric and staple the liner into place. This allows water to escape but soil to remain within the bed. If you have constructed your retaining wall with cement blocks or metal materials then consider another drainage method, the French drain.

Dig a small trench from the base of the planting bed's frame to an area of lower elevation. The trench does not have to be more than 1 foot deep and the length will vary depending on the gardener's needs. Line the trench with gravel, loose stones, broken masonry or other porous material. Cover the trench with mulch, sod or loose soil. The trench provides an escape route for excess water.

Waterlogged soil, such as clay-based soils, will not give up moisture even when offered an escape route. Clay soil is composed of fine particles with low porosity. You can check the porosity of your soil by digging a small hole, filling the hole with water and checking to see if the water drains within 15 minutes. If the water does not drain then you are working with compacted, clay or other non-porous growing medium. If this is the case and you intend on filling your bed with garden soil then construct your raised bed a bit higher than the average height of 8 to 12 inches. Be aware that using garden soil in a raised bed is not recommended by Texas A&M's Extension service. The soil tends to be heavy. This causes damage to the bed's frame. Lightweight soil mixes are a good investment. The frame will not become damaged and the soil can be worked easily.